Ibukun-olu Alade
Department of Epidemiology and Community Health, University of
IIorin, IIorin, Kwara State, Nigeria

INTRODUCTION

The range of various tropical climates supports a wide variety
of foods throughout the West African region, and indeed all of
sub-Saharan Africa. The ability of people in this region to feed
themselves depends to a large extent on the adequacy of moisture
or water supply. Where the water supply can support plant growth,
it is possible to raise as many as three crops a year. For
example, in Nigeria, which is the most thickly populated country
in this region, the driest northernmost regions are capable of
supporting the cultivation of livestock and cereals, such as
wheat, rice, maize, millet, and guinea-corn The wetter
middle-belt regions support the cultivation of legumes and
livestock, and the southern, typically tropical regions of the
country support the cultivation of tree crops as well as tubers
and roots but relatively little livestock production. Throughout
Africa, food choices are restricted not only by climate but also
by serious problems of communication, transportation, and
storage.

Within these limitations, the ultimate choice of food by the
consumer is a very personal one. In a country like Nigeria, where
the consumer's knowledge of nutrition and food and the resources
for making a wise choice of the latter are all rather limited, it
is instructive to set out guidelines to aid consumers to make
nutritionally advantageous choices. A number of guidelines have
already been developed, among which are the recommended dietary
allowances (RDAs) and the "basic four food groups"
(BFFG). The object of this paper is to discuss the
characteristics and purposes of some major food classification
systems as they have developed historically and to develop a
system that is appropriate to the socio-economic, geographic, and
cultural conditions that obtain in sub-Saharan African countries.

The RDAs, which represent nutritional standards for planning
and assessing dietary intake, have been defined by the Food and
Nutrition Board of the American National Research Council as the
"level of intake of the essential nutrients considered to be
adequate to meet the nutritional needs of practically all healthy
persons" (6). The BFFG system, on the other hand,
constitutes a food grouping or classification used to translate
nutritional needs as established by the RDAs into practical
guidelines for actual food intake (4). This food grouping is
determined, first and foremost, by the nutrient content; the BFFG
system reflects the availability of food, food patterns, and
local nutritional problems (4, 23). Thus, the grouping together
of foods with similar nutrient density and nutrient content makes
it possible to choose from a wide variety of alternatives if
certain seasonal foods become scarce or money is short (23).

The History of Food Classification

In 1834 William Prout, an English physician, was the first
scientist to classify foods by grouping them into "foods of
an animal or albuminous nature, foods of a vegetable or
saccharine nature and a group of fatty or oily foods" (5).
The modern system of classification was developed during World
War I because there was a considerable interest in the
dissemination of information on food and nutrition at that time.
The work of Hunt (10) around 1921 may have contributed in no
small measure to this effort. The main theme of systems of the
World War I era was that all foods could be divided into a small
number of categories, members of which could be interchanged.
These early guides were general in nature and did not attempt to
evaluate nutritive contributions within a group. They were
intended to serve as educational guides for the selection of
foods and the planning of meals. For example, the term
"protective foods," meaning milk, eggs, and vegetables,
was coined by McCollum in 1918, when the
"body-building" as well as the "protective"
values of these foods had not been completely elucidated. The use
of modern dietary standards are, therefore, an innovation of
comparatively recent times, established first in 1936 through the
League of Nations, based on the limited knowledge of nutrition at
that time (5).

Food rationing during World War II provided an impetus for the
development of a new classification system, and in 1943 the
"Basic Seven" food guide was promoted as a means of
selecting alternatives to common foods that were in limited
supply After the war the "Basic Seven" guide was
reviewed, and a revised version, known as the "National Food
Guide," was adopted in 1946 (5). The most recent food guide
appeared in 1955; it was based on the 1946 version and was called
"Food for Fitness: A Daily Food Guide." This guide
contains the basic four food groups classification already
adopted by the United States and Canada.

THE BASIC FOUR FOOD GROUPS

The BFFG system is a simple device used by nutritionists to
outline the variety of foods needed for a balanced diet that
provides the essential nutrients (22). The food groupings are:

1. the milk group - comprising all dairy products,
such as powdered milk, skim milk, fresh milk, buttermilk,
condensed milk, ice-cream, and yoghurt;
2. the meet group - including diverse food items such as
beef, veal, lamb, pork, other meats, eggs, fish, beans, peas,
ground-nuts, and other nuts and seeds;
3. the cereal and grain group - including wheat, rice,
maize, guinea-corn (sorghum), millet, and potatoes;
4. the fruit and vegetable group - including all fruits
and vegetables commonly consumed.

This classification system does not contain several food items
commonly consumed in Nigeria but includes most foods consumed in
the United States and Canada. In most parts of Nigeria, as in
most parts of Africa, the poor economy, the socio-cultural
factors, and the geographical location and distribution of food
have combined to limit the food choices of families (5). Queen
(21) has pointed out that in less-developed economies people
subsist on whatever food is available to them, including
squirrels, lizards, and camel and horse meat (7). Furthermore,
food items such as edible caterpillars, termites and other
insects, snails, and locust beans, which may not be regarded as
food items in the advanced nations and therefore do not appear in
their list of food items, are often regarded as delicacies or
regular staple food items, depending on the economic status of
the consumer. In the advanced nations, there is a strong reaction
to the eating of lizards, dogs, and insects because such
practices violate people's sensibilities (5).

In the more advanced economies, foods are processed and
enriched, thus enlarging food choices. Moreover, several
processed foods have found their way to the African table, such
as Semovita, instant fufu powder, and instant yam powder (15).
Such new processed foods are more amenable to modifications and
enrichment than their traditional counterparts and are,
therefore, expected to improve the nutritional status of the
people.

The BFFG classification of foods, despite its minor
limitations, has the major advantage of being a very simple
device. People more easily remember a few basic food groups than
a more complicated system (5). Simplicity is an especially
important consideration in a country like Nigeria, where the
level of education is limited. Thus, a classification system most
appropriate for African countries with food choices similar to
Nigeria's should be as simple as the Americo-Canadian
classification system but encompass the variety of foods
characteristic of African cultures.

THE PRESENT STATUS OF FOOD CLASSIFICATION IN NIGERIA

In most health institutions in Nigeria, foods are still
classified according to the functions they are supposed to
perform, perhaps in compliance with the Federal Government's
Nutrition Curriculum Guidelines (16). Thus, foods are classified
as "energy foods," "body-building foods,"
"protective foods," or "accessory food
substances," very much in line with the early
classifications of Hopkins and McCollum (5). Such classifications
are obviously obsolete, inapproproate, or even misleading.
Practically all common foods offer at least two or more nutrients
(table 1), and thus, each contributes substantially to the
overall nutritional balance of the individual and also performs
several functions.

From table 1, it is obvious that no single food contains all
the nutrients needed by the body in amounts sufficient to
maintain life and promote optimum growth. Nevertheless, each food
item supplies significant amounts of two or more nutrients.
Therefore, almost all foods offer bodybuilding, energy-producing,
and protective properties depending on their quantities and
qualities (nutrient densitites) and the physiological state of
the individual consuming them (4). For example, while eggs, meat,
and milk might offer excellent proteins (body-building
qualities), they (especially meat) also provide substantial
amounts of energy derived from their fat content as well as from
their proteins. They, therefore, provide greater potential energy
than the so-called carbohydrate energy foods. Furthermore, the
protein in meat may not be used primarily for tissue synthesis or
for growth unless and until the energy requirements of the
individual are met. Fat, which serves primarily as an energy
reservoir in concentrated form, is also required for (a) the
assimilation of other nutrients, especially the fat-soluble
vitamins, and (b) the synthesis of several essential compounds in
the body, including cholesterol, prostaglandins, testosterone,
and other lipid-containing hormones and compounds, which are
constituents of the normal body structures. Thus, fats are very
important in terms of the structure and protection of the body
from physical and physiologic damage.

The nutritional contribution of a given food is not limited to
one category of nutrients. Milk, for example, supplies a
significant amount of the daily requirement for protein, calcium,
and niacin. Bread, rice, and maize each contribute mainly
carbohydrates, in addition to substantial proportions of the
daily protein requirement, especially when large quantities are
consumed. Furthermore, when each of these foods which are limited
only in Iysine and the sulphurcontaining amino acids, is combined
with a legume, the resultant diet, together with the typical
African sauce, constitutes a very important source of proteins of
reasonably high quality, as well as vitamins and minerals. It has
been estimated that the so-called starchy energy foods, such as
the cereals, provide more than 50 per cent of the protein
requirements of a normal human diet (24). Thus, it is the
combined effect of all the nutrients in the diet that is
important, and a wide variety of foods can contribute to this
balance.

TABLE 1. Proximate Composition of Some Popular
Nigerian Foodstuffs

Food
Item
(100 g)

Protein
(g)

Carbohydrates
(g)

Fats
(g)

Ca
(mg)

Fe
(mg)

Niacin
(mg)

Milk (condensed)

12.0

?

1.8

64

1.3

8.8

Eggs (hen)

11.8

0.6

9.6

45

2.6

0.3

Beef

18.2

?

17.7

11

3.6

?

Pork

12.4

?

40.5

11

3.6

?

Chicken

20.5

?

6.5

10

1.1

?

Fish (raw mackerel)

19.0

?

1.8

64

1.3

8.8

Stock fish

21.8

?

5.4

?

?

?

Crab

31.2

9.6

7.7

1,280

?

?

Edible caterpillars

62.3

6.5

4.6

513

6.9

4.2

Ground-nuts (roasted)

23.2

21.7

50.9

42

?

15.3

Locust beans(dawadawa
or iru)

39.7

?

31.4

365

41.5

2.4

Melon seeds (egusi)

28.4

?

52

354

8.1

35.4

White bread

8.6

50.4

3.3

83.9

2.5

2.4

Millet

7.4

77.6

1.3

397

17.1

0.8

Guinea-corn

9.8

73.6

3.1

30

15.6

3.7

Rice (parboiled)

7.0

79.8

0.6

6.0

2.4

5.4

Yellow maize

10.0

73.6

4.8

13

4.9

1.7

White maize

9.4

73.6

4.2

16

3.6

2.2

Kokoyam

5.2l7.6

88.5

0.5

6l24

0.7

0.8

Adapted from information in references 11, 17, 19, 20, 21, and
24.

Uddoh (23) has classified Nigerian foods into twelve groups.
This grouping puts legumes, nuts, seeds, eggs, meats, poultry,
and fish into four separate groups. But on the basis of the
nutrient density of each of these food items, one could safely
place all four in one group. For example, the similarity in
protein content of these foods, shown in table 1 above, makes it
possible to place all these food items in one group. These items,
however, also contain generous amounts of carbohydrates, fats,
and calcium. Based on the dietary contribution of nutrients by
food items, the following groupings are suggested for Nigeria and
other African countries with similar socio-economic settings,
geography, and eating patterns.

A FOOD CLASSIFICATION FOR NIGERIA

Group One - Milk and Milk Products

This group is made up of all dairy products, including fresh
milk, skim milk, buttermilk, condensed milk, powdered milk, local
and foreign cheeses, butter, yoghurt, and icecream. Individuals
with varying degrees of lactose intolerance have a choice of
cheeses, buttermilk, and yoghurt. However, for those who must
watch their weight, the use of ice-cream and other
milk-containing beverages should be restricted. This group is
valued particularly for its calcium, magnesium, riboflavin,
cobalamin, and high-quality protein but is notably low in iron
and ascorbic acid.

Group Two - Meats, Fish, Nuts, and Beans

This group includes meats; poultry; fish; snails; shrimp;
termites; grubs; edible insects, such as caterpillars, locusts,
crickets, and grasshoppers; crabs and other sea products; eggs;
legumes (pulses); seeds; and nuts (22, 23). Although the
nutritional contributions of the members of the group vary, they
all provide valuable amounts of energy, protein, iron, and
B-complex vitamins. The various cuts of meat do compare
favourably with the amounts of protein available in poultry or
fish. While legumes contain only about 30 per cent of the amount
of protein available in animal protein foods of equivalent
weight, other valuable components of the various foods in this
group compare quite favourably with meats, particularly in light
of the high cost and the variable prices of the latter (22).
Furthermore, since large amounts are consumed, legumes are
perhaps the most important sources of proteins in many African
diets (1, 2, 18), partly because they are relatively cheap,
palatable, and keep fairly well (9). Thus, eggs and legumes can
be used freely to replace the higher-priced cuts of meat without
sacrificing nutrition (8). Furthermore, a greater use of legumes,
nuts, poultry, and fish would help to reduce the intake of
saturated fat that is quite abundant in meats (beef is 20-30 per
cent saturated fat, compared with poultry and fish, which contain
6 per cent and 2-8 per cent respectively) (8).

Group Three - Cereals and Grains

The separation of cereals and grains from the tubers, roots,
and starchy fruits is based on the differences in their ease of
storage (3) and protein content (8). Although they are of plant
origin, the group-three foods contribute not only carbohydrates
but also the B-complex vitamins, iron, magnesium, and generous
amounts of protein and energy to the diet (8, 9). Members of this
group include bread and other wheat products such as Semovita,
rice, maize, guineacorn, and millet. It is believed that there is
hardly any village in Africa where one cereal or another is not
used as a staple (9). As a group, cereals constitute the most
important food for peoples all over the world (23), with
approximately half of the people in the world depending heavily
on rice. The survival of the peoples of the Sahel regions has
been attributed to the use of cereals, limited only in Iysine and
the sulphur-containing amino acids (9).

Group Four - Hoots, Starchy Fruits, and Tubers

The members of this group include yams, sweet potatoes,
cassava, plantains, and breadfruit They are the common staples in
the wetter, more humid regions of Africa ( 10), but they are
readily perishable and cannot be stored for long periods of time.
Because of storage limitations, they are seasonal foods (3). As a
group, they are mainly starchy foods and major sources of readily
available energy, with high caloric densities. They supply about
385 kilocalories per 100 grams of dry matter and very low amounts
of other nutrients. Thus, they are limited in their contribution
to the provision of a balanced diet (9).

Group Five - Fruits and Vegetables

This group provides nutritionally important quantities of the
water-soluble vitamins, especially folic and ascorbic acids,
carotene (the precursor of vitamin A), and minerals (8).
Furthermore, many members of this group make substantial
contributions of roughage to the diet in the form of cellulose
(8). Fruits have low protein content, while the protein content
of vegetables, often ignored, may be significant (19). The common
fruits include mangoes, pawpaws, guavas, coconuts, oranges,
grapefruit, tangerines, bananas, pineapples, imported apples,
African pears, cashew fruits, avocado pears, and watermelon (3,
8). The common vegetables include turnip greens, mustard greens,
kale, spinach, mushrooms, pumpkins, onions, okra, collard greens,
bitter leaf, water leaf, carrots, tomatoes, cabbage, and lettuce
(3, 8). Unfortunately, many of these are still regarded only as
optional supplementary foods (3), perhaps because of their
seasonality and relatively high cost.

In general, the group-three foods (cereals and grains) and
group-four foods (roots, starchy fruits, and tubers) constitute
the largest portion of the typical Nigerian diet. These two
groups of foods, especially the latter, because of their limited
contributions to a balanced diet, are usually, and should always
be, consumed with the typical African sauce. The African sauce is
an extraordinary mixture of many ingredients, including
vegetables, tomatoes, peppers, oil, salt and Maggi (MSG) cubes,
meats, mushrooms, seed meals, and several other condiments and
spices. This sauce, thus, serves as an important source of
proteins, vitamins, and minerals of reasonably high quality (9)
when consumed with the staple foods as shown in table 2.

Limitations of the Classification System

Foods like alcohol, sugar, cooking oils, soft drinks,
margarine, and several components of African soup, which are
either high in fats and oils or sugar but low in other nutrients,
have not been included in the five food groups described in this
paper. Some of these items are sometimes referred to as
"empty-calorie" foods (5), so called because a food
must contain more than one essential nutrient.

TABLE 2. The Utilizable Protein Content of Some
Staples and the Diets Based on Them

Protein
Content (ND cal %)

Alone

In diets

Cassava

0.9

4.0

Maize

4.7

6.2

Rice

4.9

6.4

Guinea-corn

4.9

8.4

Millet

5.3

11.5

Adapted from refs. 14 and 17.

Major Criticisms that may be levied against this
classification are that (a) the nutritional needs of every
individual in the population cannot be met by this
classification; (b) not all food items available in a complex,
multinational country like Nigeria are encompassed by this
classification system since these usually do not follow the
nutrient pattern of any one food group; and (c) the foods of
certain ethnic groups within the society may not meet any
reasonably simple classification, and these have to be left out.

Despite these limitations, the classification is a rough but
good system that allows consumers and health professionals to
make a quick and easy evaluation of the intake of essential foods
in order to plan a diet that offers the basic nutrient
requirements for optimal health.

ACKNOWLEDGEMENTS

I wish to acknowledge the valuable contributions of my
colleagues Professor O. K. Alausa (Department of Epidemiology and
Community Health, University of IIorin) and Dr. David Atte
(Department of Geography, University of IIorin).